Suspension systems

ABSTRACT

A rotatable member for a suspension system comprises a hub and a rim joined by at least two compliant spoke structures each having two portions connected in series at an angle to each other between hub and rim and each portion having two substantially parallel spoke members forming a compliant parallelogram arrangement.

United States Patent Moore SUSPENSION SYSTEMS [72] Inventor: John Russell Crompton Moore, Little Melton, Norwich, England I22] Filed: May 21,1971

[21] Appl. No.: 147,382

[30] Foreign Application Priority Data May 28, 1970 Great Britain ..25,857/70 I521 US. Cl. ..152/75, 152/69, 152/72 [51] Int. Cl. ..B60b 9/04 [58] Field of Search ,.152/72, 69, 80, 75, 81, 71, 152/17, 12,40

[56] References Cited UNITED STATES PATENTS 1,166,697 1/1916 Likely ..'..152/69 X.

[ 1 Dec. 5, 1972 1,199,346 9/1916 Carpenter ..152/75 X 1,211,504 l/l9l7 Thuren ..l52/72 1,399,220 12/1921 McCluskey ..l52 /80 X Primary Examiner-James B. Marbert Assistant Examiner-Jerold M. Forsberg Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A rotatable member for a suspension system comprises a hub and a rim joined by at least two compliant spoke structures each having two portions connected in series at an angle to each other between hub and rim and each portion having two substantially parallel spoke members forming a compliant parallelogram arrangement.

20 Claims, 13 Drawing Figures iATENTED nan 5 m2 saw a nr 4 FIGS FIG-.5

PATENTED 5|972 SHEET 3 OF 4 SUSPENSION SYSTEMS BACKGROUND OF THE INVENTION The present invention relates to suspension systems and is particularly concerned with compliant rotatable members, such as wheels, pulleys and gears, for such systems.

The present invention is a development of the subject of U.S. Pat. application No. 315 of 1970 now Pat. No. 3,610,652 and is primarily intended for use in conjunction with the suspension system therein described, i.e. a system comprising a rotatable member having torque-transmissible compliant means joining a hub and rim of the member, the system having control means coupled to said rim by bearing means to constrain said rim to bodily movement along a predetermined path relative to a suspension support. In such a system, the difficulty arises of providing a rotatable member or wheel which does not produce cyclic disturbances between its hub and rim, i.e. cyclic angu- LII lar changes between hub and rim, when the hub is offi set from the rim.

An object of the present invention is to provide a conformable rotatable member in which, for a given hub deflection range, the hub exhibits substantially no bodily angular variation relative to the rim.

If a parallelogram be hinged at its corners and one side member is fixed, then the opposite side member 4 remains parallel to said one member when it is moved SUMMARY OF INVENTION According to the present invention, there is provided a rotatable member having a hub and a rim and torquetransmissible compliant means joining the hub and rim, the compliant means comprising at least two spoke structures each comprising first and second spoke portions coupled in series at an angle to each other between the hub and rim and each portion comprising two members each mounted at two distinct mounting regions, the mounting regions at the series junction of the spoke portions being joined so that the four mounting regions of each spoke portion are substantially at the corners of a parallelogram, as seen axially of the member.

The four mounting regions of each spoke portion are not necessarily precisely at the corners of a parallelogram, as some difference may be desirable to compensate for non-linearity in a particular suspension system.

Preferably the angle between the lines joining the two distinct mounting regions of each member of the first portion and the corresponding lines of the second portion is in the region of 90.

The junction where two portions are coupled in series may be defined by a junction device which forms part of one of the spoke portions or which is a separate component introduced between the two portions. Such a device forms a common member which may complete the parallelograms of the portions along substantially a common line or may complete the parallelograms along distinct lines. In any case, each spoke portion provides a parallelogram configuration, and one extends between the hub and the junction of the portions and the other extends between the rim and the junction.

If a wheel is constructed with such spoke structures, it will be found that when the hub is deflected from a coaxial position with the rim in a given direction, those parts of the rim which lie along the line of this deflection path maintain their angular relationship with the hub, and if the partsthat permit this deflection are of appropriate transverse stiffness substantially precise hub and rim alignment in a radial plane will be maintained. All parts of the rim not on the line of the deflection-path undergo angular displacement relative to the hub. Put another way, an arc coaxial with the axis of the hub remains parallel to an arc coaxial with the axis of the rim only along the line of deflection.

In the suspension system described above, the characteristics just described would ensure a positive drive substantially free from cyclic disturbances between hub and rim without the need for tie-bars between spoke structures. One can avoid angular changes of momentum betweerr'rim and hub during suspension deflections so that the torque transmitted remains constant between the propulsion means and the tire in contact with the road and is not distorted by irregularities introduced by the wheel construction. In the practical case, there may of course be residual errors in the realization of the invention. For example a circumstantial error producing a minor order of torsional irregularity will result if the tire strikes a road bump at an angle so that thecontact-patch center of the tire is out of line with the designed excursion path. For another example, deliberate errors may be introduced in optimizing the overall suspension design, such as by providing a castor angle in the suspension deflection path. Where the spoke portions are of resilient material, they would produce a spring wheel having negligible torsional resilience.

Whereas the result desired could be met in the purely geometrical sense with a single spoke structure, and this would suffice where dynamic conditions are not a problem, in the case of road wheels and the like, mechanical balance and the avoidance of severe bending and twisting strains under lateral loading requires at least two complete spoke structures and, depending on the design criteria in any particular application, three, four or five such structures disposed at radially equidistant positions may be found satisfactory.

The spoke portions described above may be of pivotally hinged construction and formed of many substantially rigid materials. Alternatively, they may be made of resilient sheet material, possibly spring steel.

Rigid spoke members may be pivoted by resilient or free bearing means of many descriptions, including rubber bushes and rubber bonded strip or flexible metallic hinges. Resilient spoke members may conveniently be fixed at their ends but they might alternatively have a combination of fixed and hinged joints. it will be understood that where two parallel and equal lengths of resilient material are fixedat a given separation to two unyielding side members, resilient deflections comparable to those possible with rigid but pivotally hinged parts are obtainable, and accordingly substantially similar geometrical movements may be provided. Further, any single spoke portion need not be limited to two parallel spoke members provided all its similarly curved path is provided for the mounting regions at the junction;

Wheels thus constructed with resilient spoke members can be self-supporting, and may bear vehicle loads especially where the vehicle concerned is of simple type or light construction, but it is otherwise preferred that they be employed in a suspension system as already described in which higher loads can be home by additional spring means, proper controls can be implemented? and a much greater effective deflectional range can be provided. Wheels constructed with rigid and freely hinged spoke members can support no loads in their unconstrained state and are intended solely for use in combination with the aforesaid suspension system. Where rigid spokes are used in combination with resilient hinges, the characteristics of the wheel compare with wheels using resilient spokes and, depending on the degree of resilience provided by the hinges, they may be used alone and are self-supporting.

in general, the least amount of space within the wheel is consumed by deflections in the spoke structures for a design of given transverse rigidity when the spoke structures are formed by direct superimposition or coupling of the spoke portions, that is to say, when both spoke portions are in the same radial plane. Where it is desired to provide in excess of four or five such structures within a wheel or there are design hindrances in a given application to the use of simple superimposition, a cross-over or staggered spoke construction may be employed. There may also be other occasions for such a spoke construction; for example, the crowding of too many separate spokes in a wheel may limit deflection by conflict between the movable parts.

Having decided the geometrical plan to be used and the number of spokes and their layout for a given application, convenient criteria on which to proceed with the design, with or without retrospective corrections to the starting basis, are transverse rigidity, torque and operational speed. The factors favoring long and thin hinges rather than short bearings of large diameter include their length, which affords maximum transverse resistance, their compactness in the radial plane of the wheel, which more readily permits a large deflection range, and the possibility of using wide, thin,

lightweight spoke parts of high lateral strength. In the case of resilient spoke members, it is convenient to determine the spoke design first by ascertaining the section necessary to resist buckling under peak torque at full deflection and centrifugal forces at maximum speeds.

Rigid spoke members may conveniently be cast or forged in light alloy, stamped from steel sheet or fabricated or moulded of non-metals such as reinforced plastics. Some such plastics have excellent bearing properties in which cases separate bushes or,other bearings could be obviated. Webs, ribs, corrugations and the like may be formed in the parts to enhance their rigidity.

A preferred arrangement of hinge comprises cylindrical rubber bushes secured by pressure or bonding or both pressure and bonding, used in a mortise or tenon type of hinge in which one part meshes with another part and a hinge-pin is inserted through both parts and the bushes. In one form of sucha hinge, separate rubber bushes in the form of short cylinders or sections of tube are inserted into each pre-formed hinge finger, the spoke parts are engaged and aligned, anti-friction washers are inserted between the several bushes, and a hinge-pin, which is advantageously tapered at its leading end, is pressed into the complete assembly, preferably with a bonding or locking agent which, while liquid,acts as a lubricant but which subsequently cures, The tapered end finally projecting through the hinge is subsequently severed. The pin diameter may be designed to compress the rubber to a desired extent. In another preferred arrangement of similar construction, substantial gaps are left between the individual hinge fingers when meshed, and a continuous length of rubber tube is drawn into the aligned hinge bores, the assembly being completed by inserting a hinge-pin. In the first example, thrust is taken by the washers between the fingers, and there is sliding friction; in the second example, movement of the hinge produces twisting in the exposed parts of rubber tube and thrust is taken-by shear forces in the tube and by tension and compression in alternate parts of the several exposed portions of rubber. The use of commercial rubber bushes is possible, but on grounds of simplicity, weight, bulk and cost the preferred forms described are considered advantageous. In addition these forms can reduce sliding friction, can be compact and free from lubrication maintenance, can have long life expectancy, good weather resistance, and excellent angular range for a given wall thickness of rubber.

Assuming two spoke members hinged as described at a mean angle of 90, if each part be deflected untilthe included angle is reduced to the individual bushes are only deflected 10 from the hinge-pin. A bush suitable for 20 deflection on the other hand would require a greater depth of rubber, resulting in higher cost, bulk, weight and transverse compliance, and by increasing the bush diameter and space consumption it would tend to reduce available range of deflection. The angles mentioned are of course merely by way of illustration.

Because of the self-return action of resilient bushes and in order to equalize the overall action, it is desirable that the hinged components should be assembled with the parts concerned substantially at the mean angle to be assumed when in use.

One economical method of forming rigid spoke parts is to extrude light alloy in a dumb-bell section which is cut into lengths determined by the transverse spoke width, bored transversely at the ends to suit the diameter of the bush to be used, and mortized or slotted in one operation with a multiple miller.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1, 3, 4, 5 and 6 show diagrammatically different embodiments of a compliant wheel;

FIG. 2 shows a part of the wheel of FIG. 1;

FIG. 7 shows a portion of a spoke member;

FIG. 8 shows a knuckle or junction member;

FIG. 9 is a view of one form of resilient hinge;

FIG. shows a cross-over spoke arrangement;

FIG. 11 shows a spoke junction of resilient sheet metal;

FIG. 12 shows a wheel with rim control means; and

FIG. 13 shows the control means of FIGURE 12.

Referring to FIG. 1, which is a diagrammatic plan of a proposed construction using hinged parts, substantially rigid spoke members 5 are hinged by pivots 4 between junction devices 3 and rim 1 and between hub 2 and junction devices 3 in such manner that rim and hub remain in proper spatial relationship when they undergo relative displacement from the coaxial condition. The hub spoke members are all of equal length and in each spoke are parallel; likewise the rim spoke members are of equal length and are parallel FIG. 2 illustrates a convenient spoke member construction for the embodiment of FIG. 1.

FIG. 3 illustrates diagrammatically one proposed layout for spring spokes which are rigidly fixed to the rim, hub and junction devices 3, and FIGS. 4, 5 and 6 show alternative lay-outs with spring spokes with fixed oints.

FIG. 7 is a view showing a dumb-bell shaped end of an extruded light alloy spoke member 5 after boring for the hinge and mortising for meshing with its complementary member. The fingers may be bushed with slidable bearings, needle-roller cartridges or the like, but preferably with rubber.

FIG. 8 is an end-on view of a knuckle or junction member 3 suitable for spoke members formed as shown in FIG. 7 and assembled with rubber bushes 6 and center-pins 7. It will be obvious that such junction devices may also be cut from extruded sections to provide completed components by boring and mortising.

FIG. 9 is a view of an alternative hinge in which the fingers of the hinge mesh with wide clearance to allow provision for a continuous rubber sleeve 6 to twist when adjacent fingers undergo relative angular displacement as the wheel rim is deflected, thus eliminating sliding surfaces between the fingers.

FIG. 10 illustrates one convenient cross-over spoke arrangement in which the hub spoke members are staggered across the hub and the rim spoke members are staggered across the rim. Clearly, by turning spoke member A to a vertical position and by lowering spoke B, such a layout could be used to stagger the radial fixing plane at the hub in relation to that at the rim.

FIG. 11 shows one method by which a junction may be formed from resilient sheet metal used for forming resilient spoke members. Each spoke pair is formed by bending the sheet metal into a U configuration in'such manner as to leave an angled limb 8 between the two members at their correct distance of separation, and the angled limbs 8 are then secured together by their facing surfaces by brazing, clamping or the like.

These examples are not'exhaustive. Marginal deviations of geometry to meetspecific requirements are possible and, for instance, the spoke members may be shaped instead of straight, the ends may be cranked to improve clearances or for other purposes, dimensional allowances may be made for resilient bush distortion when loaded, the spokes may be attached directly to the rim or the hub, or to integral parts thereof, or to parts thereto attached, and so forth. In particular, other hinge constructions may be employed, for example a .resilient hinge comprising a cylindrical or male part and a co-operating hollow cylindrical or female part open along one side and of a width determined by the angular travel requirements of the hinge. The male part is placed coaxially within the female part and rubber, such as a synthetic resin, is moulded into the annular cavity between the parts. Alternatively a split rubber tube may be drawn into the cavity and bonded to the surfaces therein.

' In all cases provision may be made for'coupling a bearing to the rim to enable the wheel to be mounted in a suspension system as described hereinbefore.

Such an embodiment is now described with reference to FIGS. 12 and 13, FIG. 12 being an axial section of a wheel with hinged spoke members 5 in the manner of FIG. 8, and FIG. 13 showing a cycloid-like lever mechanism seen in section in FIG. 12 and contained within the confines of the rim 1.

In FIG. 12, the wheel hub 2 is mounted by two bearings on a hub spindle 9 one end of which is mounted in a fixed hub carrier 10. The carrier 10 is encircled by-a brake disc secured to the hub 2. An inwardly facing flange 12 on the rim 1 co-operates with a peripheral spigot 13 of a disc 14. At the center of the disc 14 is a locking spindle 15 and nut 16, the spindle carrying a bearing 17 by which rim control means can be coupled to the rim to bypass the hub. The rim control means, to cause the rim to move in a substantially straight line relative to the hub, can take a variety of forms, such as a Watts linkage or a hypocycloid gear arrangement coupling the hub spindle 9 to the bearing 17, and also being coupled to a shaft 18 such that the shaft 18 rotates with rim deflection.

In the present embodiment, the rim control means is a lever mechanism (FIG. 13) which is equivalent to a hypocycloid gear arrangement, and thus operates to restrain the rim deflections to a substantially linear path. The mechanism comprises an arm 19 clamped to the hub spindle 9 and rotatably supporting an arm 20 at its free end. The arm 20 is pivotally coupled to one end of a lever 21 the other end of which is connected to the rim bearing 17. The center of lever 21 is pivotally connected to an arm 22 clamped to the shaft 18. Where the shaft 18 emerges from the hub carrier 10, vehicle restraint is applied to the shaft by conventional means such as a normal suspension spring. Such a spring may be designed to maintain a predetermined position of the rim relative to the hub with a predetermined load on the wheel, to take into account desired deflections for both bump and recoil. Similarly, damping means and anti-roll devices can also be applied.

Finally, it is to be noted that the above embodiments, when for a road vehicle, may be designed to provide a diametrical range for the hub in the range from at least 15 to 25 percent of the effective outer diameter of the spoke structures or of the inner diameter of whatever the structures are attached to, be it the rim or means attached to the rim.

lclaim:

1. In a rotatable member having a hub and a rim and torque-transmissible compliant means comprising at least two spoke structures joining said hub and. rim, the improvement which comprises:

each of said spoke structures having two spoke portions;

each of said spoke portionscomprising two spoke members each mountedat two distinct mounting regions; and

means joining said two spoke portions in series at an angle to each other so that the four of said mounting regions of each of said spoke portions are substantially at the corners of a parallelogram as seen axially of said member.

2. A member according to claim 1, wherein at least some of said mounting regions comprise hinges.

3. A member according to claim 2, wherein at least some of said hinges are freely pivotable hinges.

4. A member according to claim 2, wherein at least some of said hinges are resilient hinges.

5. A member according to claim 4, wherein each of said resilient hinges comprises two parts relatively rotatably mounted and a resilient member bonded between said parts.

6. A member according to claim 4, wherein each of said resilient hinges comprises two relatively rotatable parts having interdigitate, hollow, fingers, a hinge-pin which passes through said fingers, and at least one resilient bush interposed in a compressed condition between saidhinge-pin and said fingers.

7. A member according to claim 6, wherein washers are interposed between adjacent ones of said fingers.

8. A member according to claim 6, wherein said fingers are spaced apart and said resilient bush extends regions.

13. A member according to claim 12, wherein each of said spoke portions is a sheet of resilient material formed in U-shape the limbs of which are said spoke members and the bight of which forms a junction by which said portion is secured in series to the associated one of said spoke portions.

14. A member according to claim 1, wherein at least one one of said spoke portions has more than two of said spoke members so arranged that said four mounting regions of any pair of said more than two spoke members are substantially at the corners of a parallelogram, as viewed axially.

15. A member according to claim 1, wherein, in each of said spoke structures, the angle between said two spoke portions is about 16. A member according to claim 1, wherein said compliant means are constructed so that said hub can deflect diametrically to at least l5 percent of the effective outer diameter of said spoke structures.

17. A member according to claim 1, and comprising a bearing coupled to said rim so that rim control means can be applied to said rim while bypassing said hub.

18. A member according to claim 17, and comprising said rim control means coupled to said rim by said bearing for restraining relative movement of said hub and rim to a predetermined path during rotation of said hub and rim.

19. A member according to claim 18, wherein said control means has a portion which moves with said relative movement so that a suspension spring can be coupled to said portion to impart resilience to said relative movement.

20. A member according to claim 19, wherein said control means is a lever mechanism simulating a cycloid mechanism. 

1. In a rotatable member having a hub and a rim and torquetransmissible compliant means comprising at least two spoke structures joining said hub and rim, the improvement which comprises: each of said spoke structures having two spoke portions; each of said spoke portions comprising two spoke members each mounted at two distinct mounting regions; and means joining said two spoke portions in series at an angle to each other so that the four of said mounting regions of each of said spoke portions are substantially at the corners of a parallelogram as seen axially of said member.
 2. A member according to claim 1, wherein at least some of said mounting regions comprise hinges.
 3. A member according to claim 2, wherein at least some of said hinges are freely pivotable hinges.
 4. A member according to claim 2, wherein at least some of said hinges are resilient hinges.
 5. A member according to claim 4, wherein each of said resilient hinges comprises two parts relatively rotatably mounted and a resilient member bonded between said parts.
 6. A member according to claim 4, wherein each of said resilient hinges comprises two relatively rotatable parts having interdigitate, hollow, fingers, a hinge-pin which passes through said fingers, and at least one resilient bush interposed in a compressed condition between said hinge-pin and said fingers.
 7. A member according to claim 6, wherein washers are interposed between adjacent ones of said fingers.
 8. A member according to claim 6, wherein said fingers are spaced apart and said resilient bush extends across gaps between said fingers.
 9. A member according to claim 2, wherein said spoke members are substantially rigid and all said mounting regions comprise hinges.
 10. A member according to claim 9, wherein all said hinges are resilient hinges.
 11. A member according to claim 1, wherein said spoke members are resilient.
 12. A member according to claim 11, wherein said spoke members are fixedly mounted at said mounting regions.
 13. A member according to claim 12, wherein each of said spoke portions is a sheet of resilient material formed in U-shape the limbs of which are said spoke members and the bight of which forms a junction by which said portion is secured in series to the associated one of said spoke portions.
 14. A member according to claim 1, wherein at least one one of said spoke portions has more than two of said spoke members so arranged that said four mounting regions of any pair of said more than two spoke members are substantially at the corners of a parallelogram, as viewed axially.
 15. A member according to claim 1, wherein, in each of said spoke structUres, the angle between said two spoke portions is about 90*.
 16. A member according to claim 1, wherein said compliant means are constructed so that said hub can deflect diametrically to at least 15 percent of the effective outer diameter of said spoke structures.
 17. A member according to claim 1, and comprising a bearing coupled to said rim so that rim control means can be applied to said rim while bypassing said hub.
 18. A member according to claim 17, and comprising said rim control means coupled to said rim by said bearing for restraining relative movement of said hub and rim to a predetermined path during rotation of said hub and rim.
 19. A member according to claim 18, wherein said control means has a portion which moves with said relative movement so that a suspension spring can be coupled to said portion to impart resilience to said relative movement.
 20. A member according to claim 19, wherein said control means is a lever mechanism simulating a cycloid mechanism. 